linux-kernel - [PATCH] x86/sgx: Declare sgx_set_attribute() for !CONFIG_X86

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Message-Id: <20210903064156.387979-1-jarkko@kernel.org>
Date:   Fri,  3 Sep 2021 09:41:56 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     Tony Luck <tony.luck@...el.com>, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH] x86/sgx: Declare sgx_set_attribute() for !CONFIG_X86_SGX

Simplify sgx_set_attribute() usage by declaring a fallback
implementation for it rather than requiring to have compilation
flag checks in the call site. The fallback unconditionally returns
-EINVAL.

Refactor the call site in kvm_vm_ioctl_enable_cap() accordingly.
The net result is the same: KVM_CAP_SGX_ATTRIBUTE causes -EINVAL
when kernel is compiled without CONFIG_X86_SGX_KVM.

Cc: Tony Luck <tony.luck@...el.com>
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
---
 arch/x86/include/asm/sgx.h | 8 ++++++++
 arch/x86/kvm/x86.c         | 2 --
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
index 05f3e21f01a7..31ee106c0f4b 100644
--- a/arch/x86/include/asm/sgx.h
+++ b/arch/x86/include/asm/sgx.h
@@ -372,7 +372,15 @@ int sgx_virt_einit(void __user *sigstruct, void __user *token,
 		   void __user *secs, u64 *lepubkeyhash, int *trapnr);
 #endif
 
+#ifdef CONFIG_X86_SGX
 int sgx_set_attribute(unsigned long *allowed_attributes,
 		      unsigned int attribute_fd);
+#else
+static inline int sgx_set_attribute(unsigned long *allowed_attributes,
+				    unsigned int attribute_fd)
+{
+	return -EINVAL;
+}
+#endif
 
 #endif /* _ASM_X86_SGX_H */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e5d5c5ed7dd4..a6a27a8f41eb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5633,7 +5633,6 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 			kvm->arch.bus_lock_detection_enabled = true;
 		r = 0;
 		break;
-#ifdef CONFIG_X86_SGX_KVM
 	case KVM_CAP_SGX_ATTRIBUTE: {
 		unsigned long allowed_attributes = 0;
 
@@ -5649,7 +5648,6 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 			r = -EINVAL;
 		break;
 	}
-#endif
 	case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:
 		r = -EINVAL;
 		if (kvm_x86_ops.vm_copy_enc_context_from)
-- 
2.25.1